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The Physiological And Ecological Response Characteristics Of The Dominant Plant Rumex Japonicus Houtt. In Riparian Zone Under The Stress Of Artificial Defoliation

Posted on:2019-07-24Degree:MasterType:Thesis
Country:ChinaCandidate:T T WangFull Text:PDF
GTID:2370330545967909Subject:Ecology
Abstract/Summary:PDF Full Text Request
The aim of the the study was to explore the morphological and physiological change rules and characteristics response of the Rumex japonicus under the stress of artificial defoliation and provide basis for the remediation of wetland vegetation ecosystem which is severely damaged by herbivory stress.The dominant plant Rumex japonicus in riparian zone were collected from the riparian zone of the Poyang Lake and Le'an River as the materials,soil pot experiment and artificial defoliation simulated herbivory stress was conducted to explore the variation and comparison of morphology,chlorophyll content,chlorophyll fluorescence,photosynthetic parameters and enzyme activity index of Rumex japonicus under periodic continuous defoliation of two different defoliation patterns of 3 defoliation intensity.The results showed as belows:1.The number of leaves,plant height,biomass,root length of Rumex japonicus of A defoliation pattern which defoliated by the leaf area has an great increasement by contrast with the N defoliation pattern which defoliated by the number of leaf,but increasement decreased with change of intensity and time.Plant height,root length of Rumex japonicus under 25%and 50%defoliation intensity of A defoliation pattern has an increasement over that of control group,the number of leaves,biomass of Rumex japonicus under 25%defoliation intensity of A defoliation pattern has an increasement over that of control group,but all growth index of Rumex japonicus under 75%defoliation intensity was below that of control group,the gap between the other growth indexes and the control group was not significant except biomass.All growth index of Rumex japonicus of N defoliation pattern were lower than that of control group,but Difference was not obvious,it's growth index was higher than that of control group at the early defoliation stage,while then its'growth index was lower than the control group;N defoliation pattern significantly reduced the biomass of Rumex japonicus.The A defoliation pattern promoted the growth of Rumex japonicus,the promotion effect decreased with the increased intensity of defoliation intensity.The growth state of Rumex japonicus was restrain under the N defoliation pattern,the restrain effect was significantly increased with the increase of defoliation intensity.2.The change trend of chlorophyll a,chlorophyll b and total chlorophyll content of Rumex japonicus showed double peaks,the content of chlorophyll were higher than the adjacent processing period in second weeks and sixth weeks.The chchlorophyll content was lower than that of control group,the gap was significant by the increase in the intensity of the defoliation of N defoliation pattern.The content of chlorophyll under the 25%and 50%intensity defoliation stress group was significantly higher than control group,and the 75%intensity defoliation was lower than that of control group of A defoliation pattern.The chlorophyll content correlation index analysis showed that the chlorophyll content of Rumex japonicus was negatively correlated to those of N defoliation pattern,the correlation of A defoliation pattern and the chlorophyll content of Rumex japonicus was not obvious.The variation of value of Fo decreased parabolicly,but the time of different defoliation intensity reaches the maximum value was different,25%and 50%intensity defoliation reached the maximum at fourth weeks,the 75%treatment reached the maximum in the second week,the time treatment group of A defoliation pattern reached maximum value was opposite to that of the N defoliation pattern.The value of Fm,Fv,Fo/Fv,QYmax,Fv/Fmlss,NPQlss of Rumex japonicus under herbivory stress increased,the above indexes of 25%N defoliation stress groups were lower than that of 25%A defoliation stress groups,the contrast of other defoliation intensities is opposite to the 25%defoliation intensity.The chlorophyll fluorescence parameters of Rumex japonicus were increased by herbivory,the chlorophyll fluorescence parameters of N defoliation pattern under mild intensity herbivory stress were higher than those of A defoliation pattern,the contrast relationship between the two defoliation patterns under moderate and severe intensity herbivory stress was opposite.The artificial defoliation stress increased net photosynthetic rate?Pn?of Rumex japonicus,Pn of treatment group of N defoliation pattern is higher than that of A efoliation pattern.The change of Pn was mainly restricted by stomatal conductance?Gs?.3.The activity of the SOD enzyme activity increased gradually over time,and the activity of the SOD enzyme activity under the N defoliation pattern was greater than that of A defoliation pattern under 25%and 50%defoliation intensity,however the SOD enzyme activity of 75%defoliation intensity was contrary.The POD and CAT enzyme activity of all defoliation intensity of pattern A is greater than the pattern N,but the change trend is different.CAT activity of two defoliation patterns of the 75%defoliation intensity were lower than other defoliation intensity,CAT enzyme activity showed a parabolic trend.Herbivory stress increased the activity of Rumex japonicus protective enzyme,but the increasement decreased with the increase of herbivory intensity.The resistance of Rumex japonicus antioxidant enzyme protection system to A defoliation pattern was stronger than that of N defoliation pattern.The above results showed that Rumex japonicus had a good growth adaptation mechanism and antioxidant enzyme activity under the A defoliation pattern,and showed stronger photosynthesis under the N defoliation pattern,so Rumex japonicus had better adaptability to two kinds of herbivory stress,which could be used as a alternative native species for the restoration of the wetland ecosystem in the Poyang Lake and Le'an River riparian zone.
Keywords/Search Tags:Rumex japonicus Houtt., Defoliation Stress, Defoliation Pattern, Growth Index, Physiological Characteristics
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